Rubber composition for clinch or chafer, and pneumatic tire

Abstract

The present invention aims to provide a rubber composition for a clinch or chafer which enables to improve the rim chafing resistance, elongation at break, handling stability, and fuel economy in a balanced manner, and to reduce the number of broken spews in tire demolding; and a pneumatic tire produced using the rubber composition. The rubber composition for a clinch or chafer includes 100 parts by mass of a rubber component; 1.2 to 2.9 parts by mass of zinc oxide; and 2.2 to 4.0 parts by mass of stearic acid, the rubber component including 15 to 80% by mass of a butadiene rubber and 15 to 50% by mass of an isoprene-based rubber based on 100% by mass of the rubber component.

The invention claimed is: 
     
       1. A pneumatic tire comprising a clinch and/or a chafer, said clinch and/or chafer being produced from a rubber composition comprising:
 100 parts by mass of a rubber component comprising 50 to 80% by mass of a butadiene rubber and 20 to 50% by mass of an isoprene-based rubber; 
 1.2 to 2.9 parts by mass of zinc oxide based on 100% by mass of the rubber component; and 
 2.2 to 4.0 parts by mass of stearic acid based on 100% by mass of the rubber component. 
 
     
     
       2. The pneumatic tire according to  claim 1 , wherein said rubber composition further comprises
 2.0 to 5.0 parts by mass of a vulcanization accelerator for each 100 parts by mass of the rubber component, and 
 wherein 
 the amount of zinc oxide in said rubber composition is 1.3 to 2.0 parts by mass and 
 the amount of stearic acid in said rubber composition is 2.5 to 3.5 parts by mass, for each 100 parts by mass of the rubber component. 
 
     
     
       3. The pneumatic tire according to  claim 1 , wherein said rubber composition further comprises
 1.91 to 2.70 parts by mass of sulfur for each 100 parts by mass of the rubber component. 
 
     
     
       4. The pneumatic tire according to  claim 1 , wherein said rubber composition further comprises
 40 to 70 parts by mass of carbon black for each 100 parts by mass of the rubber component, and 
 wherein the butadiene rubber in said rubber component comprises a 1,2-syndiotactic polybutadiene crystal.